IRJET- Enhancement of Durability of Quarry Dust Stabilized Soft Clayey Soil using Oxides of Calcium

International Research Journal of Engineering and Technology (IRJET)

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Enhancement of Durability of Quarry Dust Stabilized Soft Clayey Soil using Oxides of Calcium and Aluminium Anjana L.R.1, Shruthi Johnson2 1M.

Tech Student, Civil Department, Marian Engineering College, TVM, Kerala, India Professor, Civil Department, Marian Engineering College, TVM, Kerala, India ---------------------------------------------------------------------***---------------------------------------------------------------------2.1 Clayey Soil Abstract - The use of quarry dust was found to be effective 2Assistant

to increase the strength of soft clayey soil. The durability of quarry dust stabilized soil is very less due to lack of bonding between soil and quarry dust. It is essential to satisfy the durability conditions for long term use of stabilized soil as subgrade especially in regions wet and dry climatic conditions prevail. This study investigated the use of Oxides of Calcium and Aluminium to enhance the durability of soft clayey soil subgrade stabilized with quarry dust. It also focuses on the effect of Calcium oxide on durability of soft clayey soil treated and not treated with Quarry dust.

The soil used for work was collected from Thonnakkal, Thiruvananthapuram, Kerala, India. The properties of soil were tested and tabulated in Table -1. Based on Indian Standard Classification System (ISCS), the soil is classified as Clay of low compressibility (CL). Unconfined compression test was conducted to confirm the soil is soft. The grain size distribution of clay was found out using hydrometer analysis (IS: 2720 (Part 4) - 1983) is shown in Chart -1.

Table -1: Properties of Clayey Soil

Key Words: Drying-wetting cycle test, Soft clayey soil, Unconfined compressive strength.

Soil Properties Specific gravity Liquid limit (%) Plastic limit (%) Shrinkage limit (%) Plasticity Index (%) IS Classification OMC (%) Percentage of clay (%) Percentage of silt (%) Percentage of sand (%) UCS (kPa)

1. INTRODUCTION Construction on soft ground area is a great challenge in the field of geotechnical engineering. Many engineering problems in the form of slope instability, bearing capacity failure or excessive settlement could occur either during or after the construction phase due to low shear strength and high compressibility of this soil [1]. Soft soil with high percentage of clay content have very strength.

In order to increase consistency(firmness) of soft cohesive clayey soil addition of cohesionless materials was found to be effective [2]. Very fine quarry dust (particle size less than 425micron) cannot be used for other purposes such as concrete works and as it is cheap and cohesionless it can be used for stabilization of soft soil.

2.2 Quarry Dust The quarry dust used in the study was collected from a local stone crushing site in pallichal, Thiruvananthapuram, Kerala, India. The collected quarry dust was first dried and screened over sieve size 4.75mm to remove any impurities. Then it was sieved through sieve size 425 micron to obtain fine quarry dust particles. The properties of fine quarry dust were tested and tabulated in Table -2. The grain size distribution of quarry dust was found out by sieve analysis (IS: 2720 (Part 4)- 1983) is shown also in Chart -1.

Due to the lack of bonding between soil and quarry dust particle the stabilized mix will not be durable under series of drying and wetting cycles. Calcium Oxide (CaO) was found to be effective to improve the strength of soft soil [3].

The present study includes the effect of CaO in treated and untreated with Quarry dust in order to compare the increase in durability and the effect of Aluminium oxide (Al2O3) on quarry dust stabilized soil treated with CaO.

Table-2: Properties of Quarry Dust Soil Properties Specific gravity Effective Size D10(mm) D60(mm) D30(mm) Co-efficient of curvature, CC Uniformity Co-efficient, Cu

2. MATERIALS USED Three different materials were used in this research: clayey soil, Quarry dust, Calcium oxide and Aluminium Oxide.

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Values Obtained 2.53 33 20.2 18.3 12.9 CL 24.5 60 36 4 28.7

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Values Obtained 2.7 0.03 0.2 0.1 1.67 6.67

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% fines below 0.425mm Angle of internal friction (Φ) Cohesion, c (kPa)

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For Mix 3: Standard Procter compaction tests were conducted to determine the optimal moisture content and maximum dry density for clayey soil mixed with different contents CaO. Cylindrical specimens of clay-CaO mix were prepared based on their respective optimal moisture content and dry density. It was allowed to cure for 14 days.

Unconfined compression test was conducted on each specimen. The specimen with maximum UCS value was selected as Mix 2.

100 470 0

100 90

Percentage finer (%)

80

For Mix 4: Standard Procter compaction tests were conducted to determine the optimal moisture content and maximum dry density for soil-quarry dust mix (Mix 2) mixed with different percentages CaO. Cylindrical specimens of clayquarry dust-CaO mix were prepared based on their respective optimal moisture content and dry density. It was allowed to cure for 14 days. Unconfined compression test was conducted on each specimen. The specimen with maximum UCS value was selected as Mix 4.

70 60

Clayey soil

50

Quarry dust

40 30 20 10 0 0.001

0.01

0.1

1

For Mix 5: Mix 4 was mixed with an excess amount of CaO and small amount of Al2O3 and standard Procter compaction tests were conducted to determine the optimal moisture content and maximum dry density. Then cylindrical specimens were prepared based on their respective optimal moisture content and dry density for unconfined compression test.

10

Particle size (mm)

Chart -1: Grain size distribution curves for clayey soil and

Quarry dust

2.3 Calcium Oxide and Aluminium Oxide Laboratory reagent grade Calcium Oxide (CaO) and Aluminium Oxide (Al2O3) was used as the binding agent.

Distilled water was used in preparing the test specimens and for curing.

3.3 Drying – Wetting Cycle Test

3. METHOD OF STUDY

When the curing was finished, the specimens were taken out to perform the dying-wetting cycling tests [4],[5]. In the drying process, each specimen was wrapped with plastic film and placed in an oven with temperature at 60 ± 1°C for 23 h.

In the subsequent wetting process, the specimen was taken out from the oven and placed on a porous stone in an immersion chamber for 1 hour. After this, distilled water was continuously added to immerse the specimen and maintained for 23 h. Finally, the specimen was taken out of the chamber followed by 1 h equilibrium. After this conduct Unconfined compression tests on one specimen of each mix. Then the procedures mentioned above were repeated for 1, 3, 5, and 7 cycles.

Cylindrical specimens were prepared using each mix (Prepare at least 8 specimens from one mix). Specimens were allowed to cure for 14 days.

3.1 Tests Conducted Following tests were conducted. a) Standard proctor test (IS: 2720 (Part 7)-1983) b) Unconfined compression test (IS: 2720 (Part 10) -1983) c) Drying wetting cycle test (ASTM D4843 - 88(2016))

3.2 Mix Design For Mix 1: Standard Procter compaction tests were conducted on clayey soil to determine the optimal moisture content. Then cylindrical specimens with 7.5cm height and 3.8cm diameter of clayey soil were prepared based on their respective optimal moisture content and dry density for unconfined compression test.

4. RESULTS AND DISCUSSIONS 4.1 Unconfined Compression Test Results for mix Design

For Mix 2: Standard Procter compaction tests were conducted to determine the optimal moisture content and maximum dry density for soil mixed with different contents Quarry dust. Cylindrical specimens of stabilized soil were prepared based on their respective optimal moisture content and dry density. Unconfined compression test was conducted on each specimen. The specimen with maximum UCS value was selected as Mix 2.

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UCS of clayey soil: UCS of clayey soil specimen was found as 28.7kPa. As it is between 25kPa and 50kPa the soil is soft and stabilization is essential.

UCS of clayey soil treated with quarry dust: The UCS values of Clayey soil treated with different percentage of

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quarry dust is given in Table -3 and the variation of UCS is given in Chart -2.

400

Table -3: Unconfined Compressive Strength of ClayQuarry Dust Mixes

300

UCS, qu (kPa)

Soil mix Clayey soil Clayey soil + 10% Quarry dust Clayey soil + 20% Quarry dust Clayey soil + 30% Quarry dust Clayey soil + 40% Quarry dust Clayey soil + 50% Quarry dust

350

UCS, qu (kPa) 28.7 78.3 101.5 119.2 150 90.5

250

CaO addition in Clayey soil

200 150

CaO addition in Clayey soil-Quarry dust (3:2) mix

100 50 0

0

1

2

3

4

5

6

7

CaO content (%)

160 140

Chart -3: Variation in Unconfined compressive strength with varying percentages of CaO in clayey soil and quarry dust stabilized clayey soil

UCS, qu (kPa)

120 100 80 60

When CaO reacts with clayey soil and water pozzolanic reaction will occur and UCS will increase. The formation of gelatinous material due to pozzolanic reaction is more in quarry dust stabilized soil due to the high amount of silica content.

40 20

0 0

10

20

30

40

50

60

Percentage of Quarry dust in Clay

Mix with Clayey soil + 4% CaO was selected as Mix 3 and Mix with Clayey soil + 40% quarry dust + 3% CaO was selected as Mix 4.

Chart -2: Variation in Unconfined compressive strength with varying percentages of quarry dust in clayey soil

UCS of quarry dust stabilized clayey soil treated with excess CaO and Al2O3: In order to find the effect of Aluminium Oxide (Al2O3) on quarry dust stabilized soil 1% Al2O3 and excess 3% CaO is added to Mix 4 to prepare Mix 5.

The UCS was found to be higher because of C3A formation by the reaction of Al2O3 with excess lime.

Addition of quarry dust in clay increases UCS of mix up to a certain limit due to filling of voids in dust by clay. But after a certain limit the clay content in that mix became insufficient to fill voids and UCS starts decreasing due to increase in void ratio.

Mix with Clayey soil + 40% quarry dust was selected as Mix 2 as it gives maximum UCS.

Table -5 shows the initial UCS at the failure of prepared mixes

UCS of clayey soil and quarry dust stabilized clayey soil treated with CaO: The UCS values of clayey soil and quarry dust stabilized clayey soil with different percentages of CaO (After 14 days curing) is given in Table 4 and the variation of UCS is given in Chart -3.

Table -5: Mix Design Summary

Table -4: Unconfined compressive strength of clayey soil and quarry dust stabilized clayey soil treated with CaO Percentage of CaO added (% by dry weight of soil) 0 1 2 3 4 5

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UCS, qu (kPa) In clayey soil 28.7 50.5 150.5 240.5 267 200.5

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In Clayey soil +40% Quarry dust 150.1 165.4 228.5 340.1 272 217.65

Impact Factor value: 7.211

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Mix

Composition

UCS, qu (kPa)

Mix 1

Clayey soil

28.7

Mix 2

Clayey soil+ 40% Quarry dust

150.1

Mix 3

Clayey soil+ 4% CaO

267

Mix 4

Clayey soil+ 40% Quarry dust + 3% CaO

340.1

Mix 5

Clayey soil+ 40% Quarry dust + 6% CaO + 1% Al2O3

390.8

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4.2 Drying-Wetting Cycle Test Results for Checking Durability

CaO mix shows a strength value even after the 7th cycle of drying and wetting.

Due to the formation of gelatinous materials quarry dust stabilized soil treated with 6% CaO and 1% Al2O3 shows high durability. It shows a higher value of UCS even after the 7th cycle of drying and wetting.



Drying-wetting cycle tests were conducted as per ASTM D4843 - 88(2016) on each mix. The results are tabulated in Table -6 and shown in Chart -4.

Table -6: Results of Drying-Wetting Cycle Test UCS, qu (kPa) Number of cycles 1 3 5 9.6 0 0 50.5 18.6 0 130.6 54.5 24.6 290.7 122.4 57.5 350.2 250.5 140.6

Mix 0 28.7 150.2 267 340.1 390.8

Mix 1 Mix 2 Mix 3 Mix 4 Mix 5

ACKNOWLEDGEMENT I would like to express my sincere gratitude to my parents and colleague for the advice and critical suggestions rendered by them. I am extremely grateful to all teachers in Department of Civil Engineering, Marian Engineering College for the help and facilities rendered during the course of this work.

7 0 0 0 23.6 88.8

REFERENCES 450

Hard

425 400

375

Very Soft

350

Soft

[1]

Mohamad, N. O., Razali, C. E., Hadi, A. A. A., Som, P. P., Eng, B. C., Rusli, M. B., and Mohamad, F. R.: “Challenges in Construction Over Soft Soil-Case Studies in Malaysia”, In IOP Conference Series: Materials Science and Engineering Vol. 136, No. 1, pp. 1-8, 2016.

[2]

Jain Suvid, R. K. M., Hemanth, K. H. N., Yashas, S. R., and Muralidhara, H. R.: “Improvement of Subgrade Strength

by Partial Replacement of M-Sand”, American Journal of Engineering Research (AJER), vol. 5, no. 7, pp.53-71, 2016.

[3]

Dash, S. K., and Hussain, M.: “Lime stabilization of soils: reappraisal”. Journal of materials in civil engineering, vl.

24, no. 6, pp. 707-714, 2011.

[4]

Ahmed, A., and Ugai, K.: “Environmental effects on durability of soil stabilized with recycled gypsum”, Cold regions science and technology, vol. 66, no.3, pp. 84-92, 2011.

[5]

Ye, H., Chu, C., Xu, L., K. Guo, K., and Li, D.: “Experimental Studies on Drying-Wetting Cycle Characteristics of Expansive Soils Improved by Industrial Wastes”, Advances in Civil Engineering, 2018.

325

medium

300

UCS, qu(kPa)

275

Stiff

Very Stiff

250

Very Stiff

225

Hard

200

175

Mix 1

150

Mix 2

Stiff

125

Mix 3

100 75

medium

Mix 4

50

Soft

25

Mix 5

Very Soft

0

0

1

2

3

4

5

6

7

8

9

Number of cycles Mix Mix Mix Mix Mix

1 :Clayey 2: Clayey 3: Clayey 4: Clayey 5: Clayey

soil soil+ soil+ soil+ soil+

40% Quarry dust 4% CaO 40% Quarry dust + 3% CaO 40% Quarry dust + 6% CaO + 1% Al2 O 3

Chart -4: Effect of drying-wetting cycle on UCS of mixes The consistency of Mix 5 remains in medium even after 7 cycles of drying and wetting. So that Quarry dust stabilized soil treated with 6% CaO and 1% Al2O3 can be used as durable material for subgrade.

5. CONCLUSIONS    

Addition of quarry dust shows a substantial increase in unconfined compressive strength of soft clayey soil.

The UCS of Clay-quarry dust mix will become zero after 5 cycles of drying and wetting which is an indication of low durability.

Durability of Clay-CaO mix is also low.

Clay-quarry dust-CaO mix shows comparatively greater durability than Clay-CaO mix. Because Clay-quarry dust-

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